This paper examines the accuracy of a new elastic-thermoviscoplastic (E-TVP) constitutive model developed based on Critical State Soil Mechanics. The model can be used for simulating the temperature dependent, and strain-rate dependent behavior of clay soils. The study compares the E-TVP behavior of a single soil element with previously published thermo-mechanical experimental results performed on saturated clay specimens at different temperatures. Suggestions regarding unloading and reloading at constant temperatures as well as thermal consolidation under constant loads are presented. A modification for unloading-reloading adds a new criterion to the volumetric thermoviscoplastic strain rate formulation. A physics-based term is added to the current specific volume of the soil to include the viscous effect induced by temperature change. These modifications improve the convergence of laboratory data and simulated model responses. Comparisons of 1 Fathalikhani, February 10, 2022 results from an earlier E-TVP model and the newly improved model provide evidence of improved predictive capabilities.

In this paper, the theoretical framework of a coupled thermo-hydro-mechanical damage model dedicated to non-isothermal unsaturated porous media is presented. The damage variable is a second-order tensor, and the model has been formulated in independent state variables. The approach combines thermodynamic and micromechanical theories. The behavior laws have been derived from a postulated expression of Helmholtz free energy. The damaged rigidities have been computed by applying the Principle of Equivalent Elastic Energy (PEEE). Internal length parameters have been introduced in the expressions of liquid water conductivity, to account for cracking effects on fluid flows. Damage has been assumed to have an isotropic influence on air and heat flows, through the inelastic component of volumetric strains. The damage model has been implemented in θ-Stock Finite Element program. Some numerical studies are conducted to the impact of the thermal and mechanical loading on the evaluation of response of the unsaturated bentonite, and investigation of model parameters effect on damage development.

This paper examines the accuracy of a new elastic-thermoviscoplastic (E-TVP) constitutive model developed based on Critical State Soil Mechanics. The model can be used for simulating the temperature dependent, and strain-rate dependent behavior of clay soils. The study compares the E-TVP behavior of a single soil element with previously published thermo-mechanical experimental results performed on saturated clay specimens at different temperatures. Suggestions regarding unloading and reloading at constant temperatures as well as thermal consolidation under constant loads are presented. A modification for unloading-reloading adds a new criterion to the volumetric thermoviscoplastic strain rate formulation. A physics-based term is added to the current specific volume of the soil to include the viscous effect induced by temperature change. These modifications improve the convergence of laboratory data and simulated model responses. Comparisons of results from an earlier E-TVP model and the newly improved model provide evidence of improved predictive capabilities.